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Keio University Spin-Off Forms Consortium to Develop New EV Prototype for Mass Market; Commercialization in 2013

Sketches of SIM-Drive concepts. Click to enlarge.

SIM-Drive Corp., a spin-off from Keio University (home of the Ellica, earlier post), announced that 34 companies and municipalities, including automakers Mitsubishi Motors Corp. and Isuzu Motors Ltd., will form a consortium to develop a new electric car prototype, with mass-market sales being the end goal.

The consortium, which includes battery cell manufacturers, auto parts companies and trading firms, aims to develop and mass-produce electric cars using technology developed by SIM-Drive. The initial target is a range of 300 km (186 miles) achieved through an efficient use of wheel motors and reduced air resistance.

SIM-Drive says it has distinctive competence in two primary areas: first, the technology of in-wheel motors (Shimizu In-wheel Motor-Drive; Hiroshi Shimizu, who is President of SIM-Drive, and the Keio University Electric Vehicle Laboratory in Tokyo created the 8-wheeled Ellica) and second, the structure, strength and weight of the hollow floor, which contains the battery pack and power electronics.

Sketches of SIM-Drive Platform for 2WD, 4WD and 8WD. Click to enlarge.

The combination of the in-wheel motors (SIM-Drive) and component built-in frame results in an extremely simple body structure, enabling an expansive above-floor space and stable running, the company says.

The SIM-Drive platform can be used for two-wheel, four-wheel and eight-wheel drive vehicles, the company says.

SIM-Drive and the consortium is targeting 2011 for the development of the prototype, with commercialization to begin in 2013.

SIM-Drive does not intend to manufacture vehicles; rather, it will transfer developed technology, and know-how to collaborative research companies. SIM-Drive’s vision is to support the automobile industry by producing components and SIM-Drive platforms for electric cars.


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For mass market affordable and practical EVs multiple electric motors is a bad idea because it is inefficient in a number of ways. One way is motor efficiency. Two or four motors are less efficient than a single large electric motor (not so for ICE). Another way of efficiency losses is through heat extraction for cabin heating using a heat pump. To extract heat from a single motor and motor controller is more efficient than extracting heat from several smaller units. Power for cabin heating is a big issue in EVs because it can consume about 3000 to 4000 watt and that will reduce EV vehicle range by 20% as a typical EV needs 15000 and 20000 watts to move the car. The point is to do it in an intelligent way using a heat pump requiring only about 600 watt to generate 3000 to 4000 watts of heat. However, for the heat pump to be efficient it must have a central source of heat such as one motor and one battery. The latter is a also a good reason not to use two separate batteries as in the Volvo C30 EV. Thermal battery management will be most efficient using one compact battery.

Using multiple motors and separate batteries in an EV will make it more expensive, less durable and most importantly it will reduce vehicle range especially in cold weather.


Very flexible design to meet variable needs.

The four (4) battery modules is an excellent idea for future growth.

In wheel motors will reduce mechanical parts/links to a minimum.

Hope that it will be affordable.

Henry Gibson

The Car does remind me of the old steam locomotives with many large wheels. Low cost, street legal and small range-extender-fuel-generator are parts of the formula for a successful plug in electric hybrid that runs mostly on batteries. Advances in lead batteries now allow lighter weight and lower cost for electric vehicles. The electronic drive systems are also too large and too expensive, but I am glad that several manufactures are now in the market to force the competition to lower prices and automate production. Fifteen kilowatts is sufficient for most automobile uses. ..HG..


I'm with Henrik


I'm not with Henrik.

As I have expressed before, with wheel motors you do not need a differential and axles. The mechanics are simpler, and you have more design freedom because you don't have the motor, axles and differential in a predetermined location between the wheels. Electric motors are highly efficient, so not much heat can be harvested from them anyway.

Heating has never been much of an issue in ICE cars, because there is ample waste heat available. Their design has therefore never been optimized with energy efficient heating in mind. With electric cars this will have to change. Cars will be insulated and a heat exchanger will be used to harvest heat from the expelled cabin air. My guess is that the 3-4 kW that Henrik mentions is much more than a future EV needs for heating.

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Time will eventually show whether a central motor or multiple in-wheel motors will be the preferred solution for mass market EVs. For off-roaders and for racing cars I think that the advantages of individually controlled in-wheel motors may be preferred mainly because of the better handling we should expect with such a drive train design.

The 3000 to 4000 watt for cabin heating is needed in cold weather. I got the information from a company that sells EV converted Fiat vehicles in Denmark (converted by Italian Micro-Vett). (1) They install a gasoline heater in all of their converted EVs with minimum 4500 watts of cabin heating power output. They argue that 4000 watt is needed to secure effective defrosting and fog removal in cold weather. They use a gasoline heater to preserve vehicle range and because their EV conversions does not have a heat pump.

I agree a small two person city EVs can do with less than 4000 watt for cabin heating and there will not be much heat to extract from a small 30kW motor anyway.

However, all fast charge EVs will need a powerful heat pump to remove heat from the battery and the power electronics when charging. When you use a 50kW level III charger you waste about 5% heat energy in the battery and another 5% in the power electronics. That is 5000 watts that needs to be removed during fast charging. During normal driving you need to remove about 2000 watt from the motor (assuming 90% efficient at 20kW) and up to 1000 watt from the battery (min 95% efficient at 20kW). I think at low speeds in city driving you cannot extract much heat from either the battery or the motor (perhaps only 1500 watt in a normal sized car).

You have a really good point about future EVs being optimized for efficient cabin heating using the heat pump to recycle cabin heat and using a better insulated cabin than is typically used in ICE vehicles that have an ample heating source available.



Having an 8 wheeled EV will only make it more expensive and less durable than a 4 wheeled EV but even a 16 wheeled EV will have less parts to break than a 2 wheeled ICE motorcycle.


With 20kW for propulsion, you can get 2 kW from the controllers.

Roger Pham

Cooling of electrical components such as motor, generator and inverter in the Prius is done via liquid coolant. The heat obtained from this coolant can be used to heat the cabin via a heat exchanger. This means that there would be little difference in heat-harvesting efficiency whether a single motor is used or multiple motors are used.

The on-board AC can double its function as a heatpump in not-too-frigid weather to supplement cabin heating. However, when it gets too cold, perhaps a portable genset (electrical genertor) designed to be removably attached to the vehicle can also double as a heater as well, thus eliminate the wasteful use of gasoline solely for the purpose of space heating.

This genset is designed with liquid cooling combined with exhaust heat recuperation also via the liquid cooling circuit, thereby would work great to provide generous amount of heat to the cabin. The liquid cooling line simply has to be connected to the vehicle's coolant circuit. This genset would work great to extend driving range in a BEV on occasions when longer range is needed, allowing a smaller battery to reduce cost and weight. In Northern climates in which winters may last up to 6 months, this genset/heater is a must for practical adaptation of the BEV. When cabin is warmed enough, the genset can be stopped to conserve gasoline.


With a small heat pump you can extract even more heat from the controllers. This would increase the amount of heat taken from the power semiconductors, lower their maximum temperature and increase their life span.

Two or four motors are less efficient than a single large electric motor (not so for ICE).
Henrik has it exactly backwards:  small IC engines suffer efficiency loss much more than small electric motors, in no small part because of greater surface-to-volume ratio causing higher heat losses per unit of air charge.
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As far as I can read most of the auto-industry is downsizing their IC engines for almost all models in order to make them more fuel efficient and reduce emissions. See for example this source (1) or this (2).

With regard to EV motor size and efficiency I was meaning that with larger EV motors you also get more options to use high-efficiency electric motor designs. Ultimately you could use a superconductive motor with 100% efficiency less the energy used to cool the motor. In this case one big motor will still be more efficient than several small superconductive motors as less energy is needed to cool one motor than several separate motors. For an example of a superconductive motor in an EV see (3).





A smaller engine will generally be more efficient than a larger one [1] for the same power, and [2] within limits.  What will not be more efficient is 4 small engines producing the same power as 1 big one, which is what you implied.


The way I see it using smaller pancake motors gives you the option of a single electric motor acting as an assist on an ICE, an intermidiate 2 motors acting either side of a transmission or on one axle or eventually one motor acting on each wheel without any transmission or ICE with all the control done with software.

Although an 8 wheel drive vehicle with two front steering axles is an interesting concept.

Check out this Ellica a Japanese 8 wheel electric car.
8 x 60kW
0-100 MPH in 7 seconds


I think I'm with Anne on this one. Human bodies create a fair amount of heat if you've got really good insulation and a heat exchanger on the air vents. You still need that first jolt of heat to get the cabin somewhat comfortable. I've heard heated seats are somewhat efficient because they put all the heat where it does the most good.

I've been attracted to in-wheel electric moters since playing the "Car Wars" game by Steve Jackson Games in the 1980's.

This design is ridiculous with 8 wheels, though.

I want to hear if the simple, light-weight frame is also safe.

Roger Pham

Each human being produces about 100-150 Watts of heat. With 4 persons on board, you can generate only 400-600 Watts of he@t!

In frigid weather, the COP of heat pump is real low. Battery electricity produced at 35% efficiency from power plants to battery and with a COP of 3 for heat pump would be no more efficient than the use of a chemical fuel to generate combined power and heat in a genset at over 90% efficiency. The use of Battery power to generate heat directly would be only 35% efficient, and would significantly reduce the range of the BEV.


If the motor controller creates 1 kWh in heat and you can get that heat with a Stirling heat pump then you have 3400 BTU per hour. With good cabin insulation and 1 to 4 passengers it should be comfortable.

fred schumacher

When I lived in Winnipeg in the early 70s, it was common to have an AC heater in the cab for warming up the car in the morning. This was plugged in to the same circuit as the engine block heater, all being fed by a standard 15 amp 110 volt circuit, so you had 1.5 kw total on a long extension chord. Winnipeg has 12,000 heating degree days. The system worked to get your car to start and the cab warmish. That's with large cars and no thermal insulation.

It's the efficiency of the total system that counts. Hub motors allow for a smaller overall vehicle with a high usable space to volume ration. No mechanicals to deal with; fewer components; lower cost. It allows for easier downsizing. In fact, the vehicle examples shown in the article are too conventional and don't exhibit what is really possible with hubmotors.

fred schumacher

Another idea from Winnipeg:

Frost shields were mandatory on side and rear windows from October to April. These were stick on clear plastic with knobs to create an air space. You put them on the inside of the window and they converted your windows into thermopane: no frost or fogging. I had a VW bus, which is the closest thing to an unheated IC engine vehicle you can have. I put frost shields on my front windows too.

Trucks in Siberia use double pane windows, front windshields included (they use flat glass). Battery powered cars will need some form of lightweight, scratch resistant double pane windows.


I favor replacing the differential in a rear wheel drive with two motors inboard. With independent rear suspension you eliminate the unsprung weight issue. You also eliminate the differential, drive shaft, transmission, engine, not to mention fuel tank, exhaust pipe, muffler, radiator...etc.


Why would' I agree with SJC,
We know that production lines are geared for drive from a differential like source and a paired esp pancake motor is that.
We know that there are issues with larger power handling that are not easil or cheaply resolved and a pancake motor has 50% component redundancy facto while a siames single axis has near 100% redundancy.
Best of all - I like it.

WHeel motors are infant technology and one day may answer all the engineering issues in a convenient robust, line ready way but we should place some weight on transformation when discussing existing production lines and entrenched and proven systems.
Think retrofit not just at the consumer end but also the manufactures convenience.


We have seen the Caterpillar D7 with this siamese E- setup and the Torodrive tractor type transmission alredy in production.
Lastly one should hope that solidstate devices for power controllers as well as batteries and drive motors dont produce more heat than can possibly be avoided.
Talk of heating vehicles (other than windscreen desisting) would raise eyebrows around here where there have been three times as many record hot days as cold on the one hundred year records according to the official bureau met stats.

I'm not expert on how many wheels are best on steam engines so I couldn't possibly comment on that.


As an aside.

Speaking of air conditioning though you may be aware of the ionic NO piston compressor some smarties on the continent have devised for compressing H2.

Im no fan of the current state of tech but the compressor they designed (and built - in production?) is ingenious.

The ionic fluid acts as an iterface piston and does not interact with H2 so it is virtually frictionless.

I haven' been able to visualise a working example of this on a standard ice engine but with a little more time and imagination it is not hard to see that a refigerant gas can be pumped from a positive displacement (or similar varying pressure) location on an ICE wich should have an embarrassment of possibilities, and you would have a no EXTRA moving part refrig compressor.

This is an elephant in the room as big as Mazda's I - smart while
I find the current state of auto air con as wastefull, ugly concept barely worthy of recognition. - Maybe thats just me? (not the ugly etc bit)


Although I agree on the design freedom aspect, I would suggest that given this freedom the opinboard timum weight distribution is along the polar axis or centrally fore / aft. The polar requirement is not in keeping with wheel motor.
weight distribution fore and aft is served best by centralising between the wheels but neither design meets this requirement but may be alleviated by appropriate battery placement.The design freedom we should all appreciate may in the hands of a thoughtful designer prefer to place as much weight inthe ideal position as liow as possible.

Some influencing factors will be ground clearance and obstacles on cambered or 'rutted?' roads. That's Aussie slang for what passes for highways where the wheel almost disappears into the worn track. That may suit a wheel motor or at least not favor a center position unless high drive shaft drop angles or large diameter wheels or even rim reduction gears ala VW Kombi bus or Unimogs.
The small wheel low clearance offerings are a real pain around here.

Just thought I'd better put my two cents worth where it may do some good.

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